Fish have receptors on their skin and head that relay stimuli to the brain and cause reflexes, such as withdrawal, when their tissue is being damaged. But this is no guarantee of genuine pain perception.
The Scottish team injected trout with a bee venom or acetic acid in the jaw. Among other reactions, the fish rubbed their lips and went into rocking motions - reactions typical of higher vertebrates and mammals undergoing the psychological experience of pain.
"Our research suggests noxious stimulation in the rainbow trout has adverse behavioural and physiological effects. This fulfils the criteria for animal pain," concludes team member Lynne Sneddon.
"These findings will stimulate necessary scientific discussion about pain perception in fish," agrees Michael Pietrock of the Institute of Inland Fisheries in Potsdam, Germany. They could also fuel controversy between animal-protection groups and anglers, he adds. Campaign groups such as People for the Ethical Treatment of Animals have long cited pain as the main argument against fishing.
But the case is far from closed. The International Association for the Study of Pain, which is affiliated to the World Health Organization, defines pain as a purely conscious experience, with a sensory and emotional component. So in order to show that a fish experiences pain, "it is necessary to show that a fish has consciousness", counters fish physiologist James Rose of the University of Wyoming in Laramie.
The new study does not do this, Rose believes: "The detection, processing and transmission of information related to injury is unconscious and not pain."
Quirin Schiermeirer is German Correspondent for the journal Nature
References
Sneddon, L.U. et al. Proceedings of the Royal Society B, (2003). Homepage
Rose, J. The Neurobehavioral Nature of Fishes and the Question of Awareness and Pain. Reviews in Fisheries Science, 10, 1 - 38, (2003). Article
Nature
30 April 2003
Original web page at Nature
